Phase separation process



United States Patent 3,334,038 PHASE SEPARATION PROCESS Roy N. Lucas,Houston, Tex., assignor to Petrolite Corporation, Wilmington, Del., acorporation of Delaware No Drawing. Filed June 1, 1964, Ser. No. 371,7379 Claims. (Cl. 204-190) This invention relates to a process of breakingpetroleum emulsions. This invention is more particularly adapted tobreaking petroleum emulsions formed in removing oil from rocks and sandssuch as for example tar sand emulsions, or other heavy crude emulsions.

Oil is often found in conjunction with various kinds of rocks and sand.Tar sands, sands which are impregnated with heavy petroleum, are foundin most areas of the world where petroleum is present such as in France,Poland, Rumania, Russia, the Middle and Far East, the USA, etc. In theUnited States the largest and richest accumulations are in Californiaand Utah although substantial deposits are found in Kentucky, Oklahomaand Texas. However, the largest and most important deposits are theAthabasca tar sands found primarily in Northern Alberta, Canada.

The Athabasca oil sands in northeastern Alberta contain one of theworlds largest reserves of recoverable oil. The amount of oil in theformation is estimated to be between 300 and 500 billion barrels. Usinga conservative estimate for the recovery ratio, there are at least 100billion barrels of marketable oil reserves.

The oil sand layer averages 150 feet in thickness and is made up oflayers of unconsolidated oil-bearing sand interspersed with clay, shaleand lignite as well as some rock and boulders. The sand is primarilyquartz with varying percentages of silt and clay. The oil saturation inthe sand varies from 3 to 18 percent; sand with oil saturation in excessof 10 percent is classed as a good grade.

The oil sand overburden, which varies from zero to 2,000 feet inthickness, dictates the method of oil recovery. With a ratio of oil sandto overburden of 1:1 or greater, some form of open-pit mining is themost economical recovery method. With a larger ratio of overburden tosand, in situ recovery methods are required. It is estimated that 4billion barrels are recoverable by open-pit mining methods. To placethis number in perspective, it should be recalled that the provenreserves in the United States do not exceed 35 billion barrels.

In general, the oil found in the formation is a heavy, viscous, lowquality hydrocarbon containing 4% sulfur and 0.4% nitrogen. The specificgravity varies from 1.002 to 1.027, i.e., the API gravity is between 9and 6. The viscosity is greater than 3,000 poise at 60 F.

In general, oil is recovered from the oil sand-s by 1) mining or (2) insitu recovery methods.

One method of separating the oil from the sand is by hot water washingwhich has been developed by the Research Council of Alberta. In thisprocess the first step is to heat and mix the oil sand into a pulpcontaining 12-l5% water. The pulp is then abruptly flooded with excesswater in a manner which involves minimum entrainment of air. The oilcollects on the surface of the water as a buoyant froth from which itcan be removed by skimming. This froth contains about by Weight ofmineral matter and about 30-35% water. A temperature of 185 F. is aboutoptimum for pulping and flooding operations.

When oil sand is mixed and heated to a pulp of 12-15% water content, theoil lies among the sand grains as oil flecks, all of which are small,and some of which are very small. On flooding the pulp with water, thecoarser of the oil flecks form bubbles and float to the surface. Thevery fine flecks do not form bubbles and remain suspended in the water.The gas phase of the froth appears to be water vapor supplemented by airto increase the pressure to that of the atmosphere.

Entrainment of air at the point of flooding the pulp causes a fiuffyfroth that is loaded with sand particles. At the Bitumount plant therewas obtained a recovery of of the oil as froth which contained 3035%water and 48% mineral matter, on a dry basis.

Another process employed for example by Abasand Oils, Ltd. is the coldwater washing process. The principles involved in the cold watertreatment are simple.

In order to increase the fluidity of the oil content of the oil sand sothat it will flow readily at room temperatures and to reduce its densitybelow that of water so it will float, a distillate such as kerosene ismixed with the oil sand. Soda ash and a Wetting agent are added to thepulp to assist the disengagement of oil and sand. The oil so treated isagitated in water. The diluted oil floats, as a Water-in-oil emulsion,and mineral matter sinks. The oil is collected and then settled toreduce its content of mineral matter and water.

At present all of the promising projects for recovery of oil from tarsands except that developed by Shell involve stripping. Shell OilCompany of Canada has developed an in situ process of removing oil fromthe tar sands wherein steam and caustic are pumped into drilled wellswhich may be summarized as follows:

Shells program involves the development of a continuous steady work loadprocess, whereby drilled wells are brought on production and abandonedin a continuous pattern. A group of 84 wells will be drilled, completedand put on production every 58 days for the life of the project,.probably a minimum of 25 years.

This program will first attain and then maintain a production rate of130,000 b./d. of bitumen, yielding a net saleable product of 100,000b./d. The minimum number of Wells operating at any one time will be1,580.

Wells will have to be drilled to an average depth of 1,000 ft. They willbe completed with a-7-inch surface casing, 4 /2 inch production casing,slotted liners within the production interval, and 2% inch tubing.

Tubing will be hung in a packer in the injection wells to provide a deadair space between casing and tubing for heat conservation. Tubing willbe hung open-ended in the production wells, so the annulus may be usedfor lifting the well by passing inert gas around the bottom of thetubing. Gas lift was selected as most suitable for the production well.

Pipe distribution systems will be needed for multiple phases of steamand inert lift gas, and gathering systems for the produced emulsion andthe lift gas. Block stations will be established in the center of eachproducing section, and each station will service 168 production and 168injection wells through a lateral piping system. Production wells willbe drilled on the unprecedented density of fouracre spacing. A centralsteam generation plant will provide injection steam.

Thus, one of the non-stripping methods for recovering oil from thesesands involves the in situ production of oil by a process which inessence comprises injecting steam and caustic under pressure to emulsifythe oil deep in the tar sands and then bringing this emulsion to thesurface by an inert gas lift. Thereupon the emulsion is then broken, andthe oil recovered therefrom.

I have now found a novel method of breaking tar sand emulsions which ischaracterized by being a combination chemical-electric treatmentemploying the chemical agents of this invention. In the preferredembodiment the chemical agent should be intimately mixed with the oilprior to electric treatment. The results of this invention areunexpected since neither chemical treatment alone, nor electrictreatment alone, nor electric treatment then chemical treatment iscapable of effecting the same result, i.e. yield a commerciallysatisfactory product by a commercially satisfactory process. Wherechemical and electrical treatment are performed simultaneously, thecombination treatment is most effective if the chemical reagent isintimately mixed in the oil at the time of electrical treatment. Thus,in practice the oil is conditioned with chemicals prior to electrictreatment. A

The demulsifiers of this invention are characterized by beingpolyesters, of alkyleneether glycols and dicarboxylic acids. Examples ofsuch polyesters are described in US. Patents 2,562,878, 2,950,299,2,943,061, 2,911,434, 3,057,890, 3,057,891, 3,057,892, 3,110,682 andelsewhere which are by reference incorporated into the presentapplication.

The alkyleneether glycols of this invention are in essence oxyalkylatedwater and can be represented by the formula where A is the radicalderived from the alkylene oxide, for example, ethylene oxide, propyleneoxide, butylene oxide, etc. and n represents the number of moles ofalkylene oxide added about 5-500 or more, for example about -200 such asabout -100, but preferably about 25 to 50. In the above formula thetotal moles of alkylene oxide added equal 211. Preferably thealkyleneether glycol should have a molecular weight of at least about1,000, such as about 1,000 to 10,000, advantageously about 1500 to 5000,but preferably 2,000 to 3,000. However, the optimum molecular weightwill vary with the specific alkylene oxides employed and the order bywhich they are added i.e. as heteropolymers (mixed oxides), as blockpolymers of more than one oxide, but each added sequentially, such asfirst 10 moles of EtO, then 25 more of PrO, then 10 moles BuO, etc. Inaddition, one or more of the blocks can be a heteric block. In general,the alkyleneether glycols are usually cogeneric statistical mixtures.

- In certain cases, it is advantageous to react alkylene oxides withWater in a random fashion so as to form a random copolymer on theoxyalkylene chain, i.e. the (OA) -OH could be AABABABBAAABB or thealkylene oxides can be reacted in an alternate fashion to form blockcopolymers on the chain, for example A B C where A is the unit derivedfrom one alkylene oxide, for example, ethylene oxide, and B is the unitderived from a second alkylene oxide, for example ethylene oxide, and Bis the unit derived from a second alkylene oxide, for example propyleneoxide, and C is the unit derived from a third alkylene oxide, forexample, butylene oxide, etc. Thus, these compounds include bisandterpolymers or higher copolymers polymerized randomly or in a block-wisefashion or in many variations of sequential additions.

Thus, the term, oxyalkylated water or alkyleneether glycol refers tocompounds derived from water as base material or its equivalent. Thus,if diethylene glycol is the base material to be oxyalkylated, it isequivalent to one mole of water and two moles of ethylene oxide,tripropylene glycol would be one mole of water and three moles ofpropylene oxide, etc. In certain instances a higher poylalkylene oxideis employed as the base material, for example polypropylene glycol 1025.The number indicates the molecular weight of the glycol which is thereaction product of the number of moles of propylene oxide reacted withone mole of water necessary to yield a polypropylene glycol of themolecular weight indicated.

Specific examples of oxyalkylated water include the Pluronics such asdisclosed in US. Patent 2,674,619, the Ucons (carbide and carbon),2,425,845, the compositions disclosed in applications S.N. 677,907,677,908, 677,982 (all filed on Aug. 13, 1957, and now abandoned), thecomposition disclosed in patent application No. 28,216, filed May 11,1960, and now abandoned, etc.

These are, by reference, incorporated into the present application.

The terms alkyleneether glycol, polyalkyleneether glycol," andoxyalkylated water have the same meaning and may be usedinterchangeably.

It should be noted that the sum of the moles of alkylene oxide added inpreparing the polyalkyleneether glycol do not necessarily yield the truemolecular weight of the glycols. It is, therefore, preferably todetermine the molecuar weight of the glycol by hydroxy values or othermeans such as osmotic pressure. In addition, the hydroxy values give atruer value for determining the stoichiometry of reactants in preparingthe polyester. Thus, the molar value of alkylene oxide and molecularweights stated herein are those determined by hydroxy values and notnecessarily by the actual moles of alkylene oxide added. The method fordetermining hydroxy values is the Ogg, Porter & Willit modification ofthe Verley Bolsing Method for determining hydroxy values described inIndustrial Engineering Chemistry, Analytical Addition, vol. 17, pp.394-7 (1945).

The following table presents examples of polyalkyleneether-glycols whichcan be employed in this invention.

TABLE I In the table the Roman numerals indicate the order of oxideaddition: first addition (I), second (II), third addition (III). Wheremixed oxides are employed the ratios are molar ratios.

Ex. Base Material Moles EtO Moles PrO hl/lgoles Other Oxides hyleneg1ycol.- 24.6 (111).... 27.8 (11)... 10.5 (I do 37.6 (11)... 10.5 (1)..47.9 (11)... 10.5 (1).. 53.1(11)... 10.5 (1).. 64.7 (11)... 10.5 (1)..70.0 (11)... 10.5 (1).. 77.7 (11). 10.5 (1).. 77.7 (II 10.5 (1). 77.7(II). 10.5 (1) 77.7 (II)... 10.5 (1).. 77.7 (11)... 10.5 (1)-. 77.7(11). 10.5 (1).. 77.7 (11). 10.5 (1).. 37.9 (1) PrO:42.1(111).

:EtO (2.26:1.1) 101.4. EtO (0.758110) 150.27.

EtO (4.43:1.0) 43.3 (I). EtO (4.43:1.0) 40.69 (I). EtO (4.43:1.0) 123.38(1). E (3.04:1.0) 56.01 (I). EtO (3.04:1.0) 99.93 (I). EtO (0.758:1.0)47.97 (I). EtO (0.758:1.0) 85.22 (I).

Ex. Base Material Moles EtO Moles PrO 114301? Other Oxides 26 E 0 86.36(H) 16.37 (I) 27-.-. Polypropylene glycol 1025 16.0 28.... E

Dipropylene glycol 22 5 (II) 11 0 i.

z Dipopylene glycol 46 3 I o Polypropylene glycol 2025 E 0 H ODipgopylene glycol o Suitable polyesters of the above are prepared fromdicarboxylic acids such as alkane dicarboxylic acids, such as adipicacid, etc., alkene dicarboxylic acids, maleic or fumaric acid, etc.,aryl dicarboxylic acid such as the 'phthalic acids, etc., alkyleneetherdicarboxylic acids such as diglycollic acid, etc.

It is well known that when a polybasic acid, and more specifically, apolycarboxy acid, X(COOH) is reacted with a glycol, X(OH) a mixture ofpolyesters of varying molecular weights result. This reaction isgenerally written:

In actual practice, the polymeric ester product consists not of a singlematerial, compound or ester, but of a mixture of oo-generic polyesterscontaining small amounts of unreacted monomers. The number-averagemolcular weight of the product depends upon the conditions and extent ofreaction, increasing with the degree of esterification and loss of waterof reaction. It has been shown that the actual content of the variouscogeners in the polyester product may be estimated from thenumber-average molecular weight (see e.g., P. J. Flory, Chemical Review,39, 137 (1946)).

Inthe preparation of polyesters, including those employed in the presentinvention, it is not necessary to employ equal molal proportions ofpolybasic acid and glycol. However, when unequal proportions of thereactants are employed, the degree of polymerization or averagemolecular weight of the polyester product will generally be less, forgiven reaction conditions, than where equal molal proportions areemployed. This eife'ct results from the formation of end groups derivedfrom the reactant in excess, and is greater the further the proportionof reactants is from equality. In this connection it should be pointedout that, regardless of the proportions of reactants used, the polymericproduct will contain cogeners of varying end group composition. As asimple example, let us consider a dibasic acid reactant, represented byY(OH) Then the various polyesters in the product may be represented bythe following formulae, which show the three diiferent types of endgroups appearing in the cogeners:

Here'p is a whole number Which may be as low as 1 or 2, generally lessthan 40, and between about 4 and 20 in the preferred products of thisinvention. X and Y in these formulae are residues of X.(COOH) and Y(OH)joined by ester linkages. Where the polybasic acid contains three ormore carboxyl groups, the formulae representing the various polyesterproducts are, of course, more complex, but one still obtains three typesof products, from the standpoint of end-group composition, similar tothose shown for the simplified case. For purposes of this invention,polyesters also include certain monoesters which may also be formed,such as where p=1 such as O O HOYO(L}X(H)OH, HOYO( X( i-OYOH 0 o 0 0 YHO% J-X( JOYO( i-X OH and the like.

Suitable polycarboxy acids for use in preparing the presentdemulsifiers, include the commonly available organic dicarboxy andpolycarboxy acids which are resistant to decarboxylation and pyrolysisunder the usual esterification conditions. Of particular value andinterest for the preparation of the present products, are thedicarboxylic acids, such as the aliphatic dicarboxylic acids: oxalic,malonic, succinic, glutonic, adipic, pimelic, azelaic, sebacic, maleic,fumaric, diglycollic, ethylene bisdiglycollie, citroconic, itaconic,dimeric fatty acids and the like. These and similar dibasic acids areeasily reacted with the glycols specified below to yield linearpolyesters. Carbonic acid is another suitable acid reactant, but is bestemployed as its diester, such as diethyl carbonate, with whichpolyesters are formed by ester interchange and evolution of the lowboiling alcohol. Likewise, any of the polybasic acids can be used in theform of esters of low boiling monohydric alcohols. Also, the acidanhydrides, where they exist, may be used in place of the polybasicorganic acid.

Other readily usable dibasic acids include phthalic acid, terphthalicacid, isophthalic acid, and adducts of maleic acid with variousunsaturated hydrocarbons, such as diisobutylene, butadiene, retene,a-pinene and similar compounds.

Organic acids having a functionality greater than two may also beemployed to obtain polyesters suitable for use in the present process.Where such acids are used, it is necessary to control, rather carefully,the reaction conditions and/ or proportions of acid and glycol to avoidthe formation of insoluble gel-like or rubbery polyester products.Examples of suitable acids of higher functionality, include aconiticacid, hemimellitic acid, trimellitic acid, acids obtained from browncoal, maleic acid adducts of linoleic acid, and the like.

The electric treaters employed in this invention are of the conventionaltype. Illustrative examples thereof are described in the following US.patents: 2,855,359, 2,355,- 678, 2,404,405 and 987,115, which are byreference incorporated into the present application.

The electric treater may be of the turbulent or the quiescent typealthough the latter may be more satisfactory. A voltage gradientsufficient to effect satisfactory demulsification is employed, forexample a voltage gradient of about 0.3 to 15 kv./ in. or greater may beemployed, but a voltage gradient of about 2.0 to 8.0 kv./in. isgenerally preferred. Either AC or DC may be employed. By way ofillustration, the process is carried out in the following manner.

Example 1 High pressure steam and caustic are forced into the formationthrough an input well in a sort of water flooding operation. Theresulting eflluent from the output well is a tar of about 9 API (whichrepresents 30% of the product) containing less than 1% solids but about20- 30% water. The other 70% of the etfluent consists of watercontaining about 2% oil and clay. A hydrocarbon such as (4050 API)naphtha is added to dilute the tar and this product is passed throughAPI separators. The supernatant oil diluted to eight parts tar to onepart naphtha contains about 20% water.

To the supernatant oil is added the polyester of this invention whichconditions the oil. The conditioned oil is then led into an electricaltreater operated at a temperature of 250 F. and a voltage gradient of 6kv./in. wherein the phase separation is accomplished.

This product is then flashed for recovery of the naphtha diluent. Theresultant oil has a water content of less than 1% BS and W. Theresulting oil goes to visbreaking and the visbreaker products enter thepipelines whereas the visbreaker bottoms are burned as fuel to supplythe steam requirements. The oil-breaking sediment for the API separatorsis recovered by air flotation and added to the visbreaker charge withoutgoing through the dehydrator. The preferred chemical agent in thisprocess is a diglycolic polyester of Although this glycol was preparedby adding 58 moles of PrO and 14 moles of EtO to water in that order,hydroxyl values and osmotic pressure molecular weights determinationsindicate the above formula.

In addition to the use of the present invention in conjunction with thein situ production of tar sands, the invention can also be used inconjunction with resolving emulsions in other tar sand processes. Forexample, in the Great Canadian process which is a hot water process, tarsand which contains 718% oil and from 10-20% water is treated withenough diluent to equal 2 parts diluent (generally naphtha) to one partof oil in the sand and then some of the product oil (also called recyclestock) is added to make the mixture fluid enough to handle. This mixtureis thoroughly blended and the slurry run to the contactor where it ismixed with 25-30 volumes of water at about 185 F. In the contactor the 8coarse sand settles out and takes very little oil with it (about 0.2%

The oil and some of the water then flows to the oilwater separator. Asludge of solids, water and 15% oil settles to the bottom and is drivenoff. The oil, emulsion layer and some water overflow a weir and thenflow to the emulsion separator. This is primarily a tank with a bafliedividing it into two compartments. The oil and emulsion overflow thebafiie and the emulsion settles to the bottom where it is drawn off. Itconsists of about 50% oil and 50% water with fines in it. The oil isthen settled in a heater-settler.

The present invention can be used to break emulsions formed in these tarsand processes.

The emulsions of the above example are facilely broken by the preferredpolyesters of this invention which are polyesters formed from blockpolyalkyleneether glycols, for example block polyalkyleneether glycolsof propylene oxide and ethylene oxide. In the most preferred embodimentthese glycols have terminal ethylene oxide units. Thus, representativeexamples would be glycols of the formula having a molecular weight of2,0003,000 and a PrO to EtO weight ratio of approximately 2:1 to 4:1 butpreferably about 3: 1.

The preferred dicarboxylic acid employed in preparing the polyesters ofthis invention is diglycolic acid.

A specific example of a very effective polyester employed in the aboveexample is a polyester of diglycolic acid and a polyalkyleneether glycolof the general formula having a molecular weight of 2600 where theweight of PrO is about 2,000 and the weight of EtO is about 600. Thispolyester is prepared by reacting under esterifying conditionsapproximately one mole of diglycolic acid with approximately one mole ofthe glycol. It is advantageously employed in concentrations of 75-200p.p.m. at a voltage of about 5-7 kv./ in.

These chemical agents produce a product of commercially acceptable BS&Wat a commercial acceptable voltage and amperage.

The concentration of demulsifier will vary widely depending on theparticular emulsifier and the particular system employed. Thus, anyconcentration capable of demulsification according to this invention canbe employed, for example concentrations of from about 10- 10,000 ppm. orgreater, based on weight of oil treated, such as from 505,000,advantageously 75-500, but preferably about -300 p.p.m. Naturally, onedesires to employ the minimum amount of demulsifier capable of achievinga commercial result; so that although larger concentrations may beemployed there is generally no advantage in doing so. It is oftenadvantageous to employ solutions of the demulsifier.

In addition to the use of the present invention in the recovery of oilfrom Athabasca tar sand, the invention can be employed in the recoveryof oil from oil-bearing sands and shale in other parts of the world suchas in the US. where emulsions are a problem, for example in the oil sandof California and Utah.

As is quite evident, new polyesters will be constantly developed whichcould be useful in this invention. It is, therefore, not only impossibleto attempt a comprehensive catalogue of such compositions, but toattempt to describe the invention in its broader aspects in terms ofspecific chemical names of polyesters used would be too voluminous andunnecessary since one skilled in the art could by following thedescription of the invention herein select a useful polyester. Thisinvention lies in the use of suitable polyesters in conjunction with anelectric field of suitable voltage and the individual compositions areimportant only in the sense that their properties can affect thisfunction. To precisely ldefine each specific useful polyester in lightof the present disclosure would merely call for chemical knowledgewithin the skill of the art in a manner analogous to a mechanicalengineer who prescribes in the construction of a machine the propermaterials and the proper dimensions thereof. From the description inthis specification and with the knowledge of a chemist, one will know ordeduce with confidence the applicability or specific polyesters suitablefor this invention by applying them in the process set forth herein. Inanalogy to the case of a machine, wherein the use of certain materialsof a construction or dimensions of parts would lead to no practicaluseful result, various materials will be rejected as inapplicable whereothers would be operative. One can obviously assume that no one willwish to use a useless polyester nor will be misled because it ispossible to misapply the teachings of the present disclosure to do so.Thus, any polyester-electrical system that can perform the functionstated herein can be employed.

This process, in addition to being employed in the recovery of oil fromtar sands, can also be employed in the recovery of very heavy oils, suchas heavy crudes, by similar processes. For example, certain heavy crudeswhich are so difiicult to recover by conventional procedures (so thatthey have been deemed noncommercial reserves) may be recovered bymethods similar to the steam injection method employed by Shell OilCompany described above. Thus, when heavy crudes, for example thosefound in East Texas, in California and elsewhere, are treated bysecondary recovery methods utilizing steam injection, the oil producedcan be Idemulsified by the chemical of this invention in conjunctionwith an electric field. Thus, the present process and claims include thedemulsification of these steam injection treated heavy crudes recoveredby secondary recovery methods.

Having thus described my invention what I claim as new and desire toobtain by Letters Patent is:

1. A chemical-electric process of demulsifying petroleum characterizedby subjecting petroleum emulsions, containing a polyester ofpolyalkyleneether glycol and a polycarboxylic acid, to an electricfield.

2. A chemical-electric process of demulsifying heavy crude emulsionscharacterized by subjecting the emulsions, containing a polyester of apolyalkyleneether glycol and a polycarboxylic acid, to an electricfield.

3. A chemical-electric process of demulsifying tar sand oil emulsionscharacterized by subjecting the emulsions, containing a polyester of apolyalkyleneether glycol derived from ethylene oxide and propylene oxideand a dicarboxylic acid, to an electric field.

4. A chemical-electric process of demulsifying tar sand oil emulsionswhich is characterized by subjecting the emulsions, containing apolyester of a polyalkyleneether glycol derived from ethylene andpropylene oxides and diglycolic acid, to an electric field.

5. The process of claim 4 where the polyalkyleneether glycol which has amolecular weight of 500-5000 and a weight ratio of ethylene oxide topropylene oxide to about 1:4 to 1:2 is an oxyethylatedpolypropyleneether glycol.

6. The process of claim 5 where the molecular weight of thepolyalkyleneether glycol is 2000-3000.

7. The process of claim 6 where the polyalkyleneether glycol has amolecular weight of 2500-2700 and an ethylene oxide to propylene oxideweight ratio of approximately 1:3.

8. A chemical-electric process of demulsifying tar sand emulsions whichis characterized by subjecting the emulsions, containing a polyester ofa polyalkyleneether glycol of the approximate formula and diglycolicacid, to an electric field.

9. A chemical-electric process of demulsifying heavy crude emulsionswhich is characterized by subjecting the emulsions, containing apolyester of a polyalkyleneether glycol of the approximate formula)1v.5( )7 ]z and diglycolic acid, to an electric field.

References Cited UNITED STATES PATENTS 2,050,925 8/1936 Groote 2042,447,530 8/ 1948 Perkins 204-190 2,755,296 7/ 1956 Kirkpatrick 252-3583,200,059 8/ 1965 Mills 204186 JOHN H. MACK, Primary Examiner. T.TUFARIELLO, Assistant Examiner.

1. A CHEMICAL-ELECTRIC PROCESS OF DEMULSIFYING PETROLEUM CHARACTERIZEDBY SUBJECTING PETROLEUM EMULSIONS, CONTAINING A POLYESTER OFPOLYALKYLENEETHER GLYCOL AND A POLYCARBOXYLIC ACID, TO AN ELECTRICFIELD.